/* FCrypt encryption algorithm
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 * Based on code:
 *
 * Copyright (c) 1995 - 2000 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdint.h>
#include <stdio.h>
#include "../include/fcrypt.h"

/* Rotate right two 32 bit numbers as a 56 bit number */
#define ror56(hi, lo, n)                                                       \
    do {                                                                       \
        uint32_t t = lo & ((1 << n) - 1);                                      \
        lo = (lo >> n) | ((hi & ((1 << n) - 1)) << (32 - n));                  \
        hi = (hi >> n) | (t << (24 - n));                                      \
    } while (0)

/* Rotate right one 64 bit number as a 56 bit number */
#define ror56_64(k, n)                                                         \
    do {                                                                       \
        k = (k >> n) | ((k & ((1 << n) - 1)) << (56 - n));                     \
    } while (0)

/*
 * Sboxes for Feistel network derived from
 * /afs/transarc.com/public/afsps/afs.rel31b.export-src/rxkad/sboxes.h
 */
#undef Z
#define Z(x) (x << 3)
static const uint32_t sbox0[256] __attribute__((aligned(64))) = {
    Z(0xea), Z(0x7f), Z(0xb2), Z(0x64), Z(0x9d), Z(0xb0), Z(0xd9), Z(0x11),
    Z(0xcd), Z(0x86), Z(0x86), Z(0x91), Z(0x0a), Z(0xb2), Z(0x93), Z(0x06),
    Z(0x0e), Z(0x06), Z(0xd2), Z(0x65), Z(0x73), Z(0xc5), Z(0x28), Z(0x60),
    Z(0xf2), Z(0x20), Z(0xb5), Z(0x38), Z(0x7e), Z(0xda), Z(0x9f), Z(0xe3),
    Z(0xd2), Z(0xcf), Z(0xc4), Z(0x3c), Z(0x61), Z(0xff), Z(0x4a), Z(0x4a),
    Z(0x35), Z(0xac), Z(0xaa), Z(0x5f), Z(0x2b), Z(0xbb), Z(0xbc), Z(0x53),
    Z(0x4e), Z(0x9d), Z(0x78), Z(0xa3), Z(0xdc), Z(0x09), Z(0x32), Z(0x10),
    Z(0xc6), Z(0x6f), Z(0x66), Z(0xd6), Z(0xab), Z(0xa9), Z(0xaf), Z(0xfd),
    Z(0x3b), Z(0x95), Z(0xe8), Z(0x34), Z(0x9a), Z(0x81), Z(0x72), Z(0x80),
    Z(0x9c), Z(0xf3), Z(0xec), Z(0xda), Z(0x9f), Z(0x26), Z(0x76), Z(0x15),
    Z(0x3e), Z(0x55), Z(0x4d), Z(0xde), Z(0x84), Z(0xee), Z(0xad), Z(0xc7),
    Z(0xf1), Z(0x6b), Z(0x3d), Z(0xd3), Z(0x04), Z(0x49), Z(0xaa), Z(0x24),
    Z(0x0b), Z(0x8a), Z(0x83), Z(0xba), Z(0xfa), Z(0x85), Z(0xa0), Z(0xa8),
    Z(0xb1), Z(0xd4), Z(0x01), Z(0xd8), Z(0x70), Z(0x64), Z(0xf0), Z(0x51),
    Z(0xd2), Z(0xc3), Z(0xa7), Z(0x75), Z(0x8c), Z(0xa5), Z(0x64), Z(0xef),
    Z(0x10), Z(0x4e), Z(0xb7), Z(0xc6), Z(0x61), Z(0x03), Z(0xeb), Z(0x44),
    Z(0x3d), Z(0xe5), Z(0xb3), Z(0x5b), Z(0xe),  Z(0xd5), Z(0xad), Z(0x1d),
    Z(0xfa), Z(0x5a), Z(0x1e), Z(0x33), Z(0xab), Z(0x93), Z(0xa2), Z(0xb7),
    Z(0xe7), Z(0xa8), Z(0x45), Z(0xa4), Z(0xcd), Z(0x29), Z(0x63), Z(0x44),
    Z(0xb6), Z(0x69), Z(0x7e), Z(0x2e), Z(0x62), Z(0x03), Z(0xc8), Z(0xe0),
    Z(0x17), Z(0xbb), Z(0xc7), Z(0xf3), Z(0x3f), Z(0x36), Z(0xba), Z(0x71),
    Z(0x8e), Z(0x97), Z(0x65), Z(0x60), Z(0x69), Z(0xb6), Z(0xf6), Z(0xe6),
    Z(0x6e), Z(0xe0), Z(0x81), Z(0x59), Z(0xe8), Z(0xaf), Z(0xdd), Z(0x95),
    Z(0x22), Z(0x99), Z(0xfd), Z(0x63), Z(0x19), Z(0x74), Z(0x61), Z(0xb1),
    Z(0xb6), Z(0x5b), Z(0xae), Z(0x54), Z(0xb3), Z(0x70), Z(0xff), Z(0xc6),
    Z(0x3b), Z(0x3e), Z(0xc1), Z(0xd7), Z(0xe1), Z(0x0e), Z(0x76), Z(0xe5),
    Z(0x36), Z(0x4f), Z(0x59), Z(0xc7), Z(0x08), Z(0x6e), Z(0x82), Z(0xa6),
    Z(0x93), Z(0xc4), Z(0xaa), Z(0x26), Z(0x49), Z(0xe0), Z(0x21), Z(0x64),
    Z(0x07), Z(0x9f), Z(0x64), Z(0x81), Z(0x9c), Z(0xbf), Z(0xf9), Z(0xd1),
    Z(0x43), Z(0xf8), Z(0xb6), Z(0xb9), Z(0xf1), Z(0x24), Z(0x75), Z(0x03),
    Z(0xe4), Z(0xb0), Z(0x99), Z(0x46), Z(0x3d), Z(0xf5), Z(0xd1), Z(0x39),
    Z(0x72), Z(0x12), Z(0xf6), Z(0xba), Z(0x0c), Z(0x0d), Z(0x42), Z(0x2e)};

#pragma clang diagnostic ignored "-Wshift-overflow"
#undef Z
#define Z(x) ((x << 27) | (x >> 5))
static const uint32_t sbox1[256] __attribute__((aligned(64))) = {
    Z(0x77), Z(0x14), Z(0xa6), Z(0xfe), Z(0xb2), Z(0x5e), Z(0x8c), Z(0x3e),
    Z(0x67), Z(0x6c), Z(0xa1), Z(0x0d), Z(0xc2), Z(0xa2), Z(0xc1), Z(0x85),
    Z(0x6c), Z(0x7b), Z(0x67), Z(0xc6), Z(0x23), Z(0xe3), Z(0xf2), Z(0x89),
    Z(0x50), Z(0x9c), Z(0x03), Z(0xb7), Z(0x73), Z(0xe6), Z(0xe1), Z(0x39),
    Z(0x31), Z(0x2c), Z(0x27), Z(0x9f), Z(0xa5), Z(0x69), Z(0x44), Z(0xd6),
    Z(0x23), Z(0x83), Z(0x98), Z(0x7d), Z(0x3c), Z(0xb4), Z(0x2d), Z(0x99),
    Z(0x1c), Z(0x1f), Z(0x8c), Z(0x20), Z(0x03), Z(0x7c), Z(0x5f), Z(0xad),
    Z(0xf4), Z(0xfa), Z(0x95), Z(0xca), Z(0x76), Z(0x44), Z(0xcd), Z(0xb6),
    Z(0xb8), Z(0xa1), Z(0xa1), Z(0xbe), Z(0x9e), Z(0x54), Z(0x8f), Z(0x0b),
    Z(0x16), Z(0x74), Z(0x31), Z(0x8a), Z(0x23), Z(0x17), Z(0x04), Z(0xfa),
    Z(0x79), Z(0x84), Z(0xb1), Z(0xf5), Z(0x13), Z(0xab), Z(0xb5), Z(0x2e),
    Z(0xaa), Z(0x0c), Z(0x60), Z(0x6b), Z(0x5b), Z(0xc4), Z(0x4b), Z(0xbc),
    Z(0xe2), Z(0xaf), Z(0x45), Z(0x73), Z(0xfa), Z(0xc9), Z(0x49), Z(0xcd),
    Z(0x00), Z(0x92), Z(0x7d), Z(0x97), Z(0x7a), Z(0x18), Z(0x60), Z(0x3d),
    Z(0xcf), Z(0x5b), Z(0xde), Z(0xc6), Z(0xe2), Z(0xe6), Z(0xbb), Z(0x8b),
    Z(0x06), Z(0xda), Z(0x08), Z(0x15), Z(0x1b), Z(0x88), Z(0x6a), Z(0x17),
    Z(0x89), Z(0xd0), Z(0xa9), Z(0xc1), Z(0xc9), Z(0x70), Z(0x6b), Z(0xe5),
    Z(0x43), Z(0xf4), Z(0x68), Z(0xc8), Z(0xd3), Z(0x84), Z(0x28), Z(0x0a),
    Z(0x52), Z(0x66), Z(0xa3), Z(0xca), Z(0xf2), Z(0xe3), Z(0x7f), Z(0x7a),
    Z(0x31), Z(0xf7), Z(0x88), Z(0x94), Z(0x5e), Z(0x9c), Z(0x63), Z(0xd5),
    Z(0x24), Z(0x66), Z(0xfc), Z(0xb3), Z(0x57), Z(0x25), Z(0xbe), Z(0x89),
    Z(0x44), Z(0xc4), Z(0xe0), Z(0x8f), Z(0x23), Z(0x3c), Z(0x12), Z(0x52),
    Z(0xf5), Z(0x1e), Z(0xf4), Z(0xcb), Z(0x18), Z(0x33), Z(0x1f), Z(0xf8),
    Z(0x69), Z(0x10), Z(0x9d), Z(0xd3), Z(0xf7), Z(0x28), Z(0xf8), Z(0x30),
    Z(0x05), Z(0x5e), Z(0x32), Z(0xc0), Z(0xd5), Z(0x19), Z(0xbd), Z(0x45),
    Z(0x8b), Z(0x5b), Z(0xfd), Z(0xbc), Z(0xe2), Z(0x5c), Z(0xa9), Z(0x96),
    Z(0xef), Z(0x70), Z(0xcf), Z(0xc2), Z(0x2a), Z(0xb3), Z(0x61), Z(0xad),
    Z(0x80), Z(0x48), Z(0x81), Z(0xb7), Z(0x1d), Z(0x43), Z(0xd9), Z(0xd7),
    Z(0x45), Z(0xf0), Z(0xd8), Z(0x8a), Z(0x59), Z(0x7c), Z(0x57), Z(0xc1),
    Z(0x79), Z(0xc7), Z(0x34), Z(0xd6), Z(0x43), Z(0xdf), Z(0xe4), Z(0x78),
    Z(0x16), Z(0x06), Z(0xda), Z(0x92), Z(0x76), Z(0x51), Z(0xe1), Z(0xd4),
    Z(0x70), Z(0x03), Z(0xe0), Z(0x2f), Z(0x96), Z(0x91), Z(0x82), Z(0x80)};

#undef Z
#define Z(x) (x << 11)
static const uint32_t sbox2[256] __attribute__((aligned(64))) = {
    Z(0xf0), Z(0x37), Z(0x24), Z(0x53), Z(0x2a), Z(0x03), Z(0x83), Z(0x86),
    Z(0xd1), Z(0xec), Z(0x50), Z(0xf0), Z(0x42), Z(0x78), Z(0x2f), Z(0x6d),
    Z(0xbf), Z(0x80), Z(0x87), Z(0x27), Z(0x95), Z(0xe2), Z(0xc5), Z(0x5d),
    Z(0xf9), Z(0x6f), Z(0xdb), Z(0xb4), Z(0x65), Z(0x6e), Z(0xe7), Z(0x24),
    Z(0xc8), Z(0x1a), Z(0xbb), Z(0x49), Z(0xb5), Z(0x0a), Z(0x7d), Z(0xb9),
    Z(0xe8), Z(0xdc), Z(0xb7), Z(0xd9), Z(0x45), Z(0x20), Z(0x1b), Z(0xce),
    Z(0x59), Z(0x9d), Z(0x6b), Z(0xbd), Z(0x0e), Z(0x8f), Z(0xa3), Z(0xa9),
    Z(0xbc), Z(0x74), Z(0xa6), Z(0xf6), Z(0x7f), Z(0x5f), Z(0xb1), Z(0x68),
    Z(0x84), Z(0xbc), Z(0xa9), Z(0xfd), Z(0x55), Z(0x50), Z(0xe9), Z(0xb6),
    Z(0x13), Z(0x5e), Z(0x07), Z(0xb8), Z(0x95), Z(0x02), Z(0xc0), Z(0xd0),
    Z(0x6a), Z(0x1a), Z(0x85), Z(0xbd), Z(0xb6), Z(0xfd), Z(0xfe), Z(0x17),
    Z(0x3f), Z(0x09), Z(0xa3), Z(0x8d), Z(0xfb), Z(0xed), Z(0xda), Z(0x1d),
    Z(0x6d), Z(0x1c), Z(0x6c), Z(0x01), Z(0x5a), Z(0xe5), Z(0x71), Z(0x3e),
    Z(0x8b), Z(0x6b), Z(0xbe), Z(0x29), Z(0xeb), Z(0x12), Z(0x19), Z(0x34),
    Z(0xcd), Z(0xb3), Z(0xbd), Z(0x35), Z(0xea), Z(0x4b), Z(0xd5), Z(0xae),
    Z(0x2a), Z(0x79), Z(0x5a), Z(0xa5), Z(0x32), Z(0x12), Z(0x7b), Z(0xdc),
    Z(0x2c), Z(0xd0), Z(0x22), Z(0x4b), Z(0xb1), Z(0x85), Z(0x59), Z(0x80),
    Z(0xc0), Z(0x30), Z(0x9f), Z(0x73), Z(0xd3), Z(0x14), Z(0x48), Z(0x40),
    Z(0x07), Z(0x2d), Z(0x8f), Z(0x80), Z(0x0f), Z(0xce), Z(0x0b), Z(0x5e),
    Z(0xb7), Z(0x5e), Z(0xac), Z(0x24), Z(0x94), Z(0x4a), Z(0x18), Z(0x15),
    Z(0x05), Z(0xe8), Z(0x02), Z(0x77), Z(0xa9), Z(0xc7), Z(0x40), Z(0x45),
    Z(0x89), Z(0xd1), Z(0xea), Z(0xde), Z(0x0c), Z(0x79), Z(0x2a), Z(0x99),
    Z(0x6c), Z(0x3e), Z(0x95), Z(0xdd), Z(0x8c), Z(0x7d), Z(0xad), Z(0x6f),
    Z(0xdc), Z(0xff), Z(0xfd), Z(0x62), Z(0x47), Z(0xb3), Z(0x21), Z(0x8a),
    Z(0xec), Z(0x8e), Z(0x19), Z(0x18), Z(0xb4), Z(0x6e), Z(0x3d), Z(0xfd),
    Z(0x74), Z(0x54), Z(0x1e), Z(0x04), Z(0x85), Z(0xd8), Z(0xbc), Z(0x1f),
    Z(0x56), Z(0xe7), Z(0x3a), Z(0x56), Z(0x67), Z(0xd6), Z(0xc8), Z(0xa5),
    Z(0xf3), Z(0x8e), Z(0xde), Z(0xae), Z(0x37), Z(0x49), Z(0xb7), Z(0xfa),
    Z(0xc8), Z(0xf4), Z(0x1f), Z(0xe0), Z(0x2a), Z(0x9b), Z(0x15), Z(0xd1),
    Z(0x34), Z(0x0e), Z(0xb5), Z(0xe0), Z(0x44), Z(0x78), Z(0x84), Z(0x59),
    Z(0x56), Z(0x68), Z(0x77), Z(0xa5), Z(0x14), Z(0x06), Z(0xf5), Z(0x2f),
    Z(0x8c), Z(0x8a), Z(0x73), Z(0x80), Z(0x76), Z(0xb4), Z(0x10), Z(0x86)};

#undef Z
#define Z(x) (x << 19)
static const uint32_t sbox3[256] __attribute__((aligned(64))) = {
    Z(0xa9), Z(0x2a), Z(0x48), Z(0x51), Z(0x84), Z(0x7e), Z(0x49), Z(0xe2),
    Z(0xb5), Z(0xb7), Z(0x42), Z(0x33), Z(0x7d), Z(0x5d), Z(0xa6), Z(0x12),
    Z(0x44), Z(0x48), Z(0x6d), Z(0x28), Z(0xaa), Z(0x20), Z(0x6d), Z(0x57),
    Z(0xd6), Z(0x6b), Z(0x5d), Z(0x72), Z(0xf0), Z(0x92), Z(0x5a), Z(0x1b),
    Z(0x53), Z(0x80), Z(0x24), Z(0x70), Z(0x9a), Z(0xcc), Z(0xa7), Z(0x66),
    Z(0xa1), Z(0x01), Z(0xa5), Z(0x41), Z(0x97), Z(0x41), Z(0x31), Z(0x82),
    Z(0xf1), Z(0x14), Z(0xcf), Z(0x53), Z(0x0d), Z(0xa0), Z(0x10), Z(0xcc),
    Z(0x2a), Z(0x7d), Z(0xd2), Z(0xbf), Z(0x4b), Z(0x1a), Z(0xdb), Z(0x16),
    Z(0x47), Z(0xf6), Z(0x51), Z(0x36), Z(0xed), Z(0xf3), Z(0xb9), Z(0x1a),
    Z(0xa7), Z(0xdf), Z(0x29), Z(0x43), Z(0x01), Z(0x54), Z(0x70), Z(0xa4),
    Z(0xbf), Z(0xd4), Z(0x0b), Z(0x53), Z(0x44), Z(0x60), Z(0x9e), Z(0x23),
    Z(0xa1), Z(0x18), Z(0x68), Z(0x4f), Z(0xf0), Z(0x2f), Z(0x82), Z(0xc2),
    Z(0x2a), Z(0x41), Z(0xb2), Z(0x42), Z(0x0c), Z(0xed), Z(0x0c), Z(0x1d),
    Z(0x13), Z(0x3a), Z(0x3c), Z(0x6e), Z(0x35), Z(0xdc), Z(0x60), Z(0x65),
    Z(0x85), Z(0xe9), Z(0x64), Z(0x02), Z(0x9a), Z(0x3f), Z(0x9f), Z(0x87),
    Z(0x96), Z(0xdf), Z(0xbe), Z(0xf2), Z(0xcb), Z(0xe5), Z(0x6c), Z(0xd4),
    Z(0x5a), Z(0x83), Z(0xbf), Z(0x92), Z(0x1b), Z(0x94), Z(0x00), Z(0x42),
    Z(0xcf), Z(0x4b), Z(0x00), Z(0x75), Z(0xba), Z(0x8f), Z(0x76), Z(0x5f),
    Z(0x5d), Z(0x3a), Z(0x4d), Z(0x09), Z(0x12), Z(0x08), Z(0x38), Z(0x95),
    Z(0x17), Z(0xe4), Z(0x01), Z(0x1d), Z(0x4c), Z(0xa9), Z(0xcc), Z(0x85),
    Z(0x82), Z(0x4c), Z(0x9d), Z(0x2f), Z(0x3b), Z(0x66), Z(0xa1), Z(0x34),
    Z(0x10), Z(0xcd), Z(0x59), Z(0x89), Z(0xa5), Z(0x31), Z(0xcf), Z(0x05),
    Z(0xc8), Z(0x84), Z(0xfa), Z(0xc7), Z(0xba), Z(0x4e), Z(0x8b), Z(0x1a),
    Z(0x19), Z(0xf1), Z(0xa1), Z(0x3b), Z(0x18), Z(0x12), Z(0x17), Z(0xb0),
    Z(0x98), Z(0x8d), Z(0x0b), Z(0x23), Z(0xc3), Z(0x3a), Z(0x2d), Z(0x20),
    Z(0xdf), Z(0x13), Z(0xa0), Z(0xa8), Z(0x4c), Z(0x0d), Z(0x6c), Z(0x2f),
    Z(0x47), Z(0x13), Z(0x13), Z(0x52), Z(0x1f), Z(0x2d), Z(0xf5), Z(0x79),
    Z(0x3d), Z(0xa2), Z(0x54), Z(0xbd), Z(0x69), Z(0xc8), Z(0x6b), Z(0xf3),
    Z(0x05), Z(0x28), Z(0xf1), Z(0x16), Z(0x46), Z(0x40), Z(0xb0), Z(0x11),
    Z(0xd3), Z(0xb7), Z(0x95), Z(0x49), Z(0xcf), Z(0xc3), Z(0x1d), Z(0x8f),
    Z(0xd8), Z(0xe1), Z(0x73), Z(0xdb), Z(0xad), Z(0xc8), Z(0xc9), Z(0xa9),
    Z(0xa1), Z(0xc2), Z(0xc5), Z(0xe3), Z(0xba), Z(0xfc), Z(0x0e), Z(0x25)};

/*
 * This is a 16 round Feistel network with permutation F_ENCRYPT
 */
#define F_ENCRYPT(R, L, sched)                                                 \
    do {                                                                       \
        union lc4 {                                                            \
            uint32_t l;                                                        \
            uint8_t c[4];                                                      \
        } u;                                                                   \
        u.l = sched ^ R;                                                       \
        L ^= sbox0[u.c[0]] ^ sbox1[u.c[1]] ^ sbox2[u.c[2]] ^ sbox3[u.c[3]];    \
    } while (0)

/*
 * encryptor
 */
void fcrypt_encrypt(struct fcrypt_ctx *ctx, uint8_t *dst, const uint8_t *src) {
    uint32_t *X = (uint32_t *)src;
    uint32_t *Y = (uint32_t *)dst;
    uint32_t Xl = *X;
    uint32_t Xr = *(X + 1);

    F_ENCRYPT(Xr, Xl, ctx->sched[0x0]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x1]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x2]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x3]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x4]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x5]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x6]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x7]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x8]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x9]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xa]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0xb]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xc]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0xd]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xe]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0xf]);

    *Y = Xl;
    *(Y + 1) = Xr;
}

/*
 * decryptor
 */
void fcrypt_decrypt(struct fcrypt_ctx *ctx, uint8_t *dst, const uint8_t *src) {
    uint32_t *X = (uint32_t *)src;
    uint32_t *Y = (uint32_t *)dst;
    uint32_t Xl = *X;
    uint32_t Xr = *(X + 1);

    F_ENCRYPT(Xl, Xr, ctx->sched[0xf]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xe]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0xd]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xc]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0xb]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0xa]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x9]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x8]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x7]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x6]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x5]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x4]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x3]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x2]);
    F_ENCRYPT(Xl, Xr, ctx->sched[0x1]);
    F_ENCRYPT(Xr, Xl, ctx->sched[0x0]);

    *Y = Xl;
    *(Y + 1) = Xr;
}

/*
 * Generate a key schedule from key, the least significant bit in each key byte
 * is parity and shall be ignored. This leaves 56 significant bits in the key
 * to scatter over the 16 key schedules. For each schedule extract the low
 * order 32 bits and use as schedule, then rotate right by 11 bits.
 */
int fcrypt_setkey(const uint8_t *key, struct fcrypt_ctx *ctx,
                  unsigned int keylen) {
#if BITS_PER_LONG == 64 /* the 64-bit version can also be used for 32-bit      \
                         * kernels - it seems to be faster but the code is     \
                         * larger */

    uint64_t k; /* k holds all 56 non-parity bits */

    /* discard the parity bits */
    k = (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key++) >> 1;
    k <<= 7;
    k |= (*key) >> 1;

    /* Use lower 32 bits for schedule, rotate by 11 each round (16 times) */
    ctx->sched[0x0] = (k);
    ror56_64(k, 11);
    ctx->sched[0x1] = (k);
    ror56_64(k, 11);
    ctx->sched[0x2] = (k);
    ror56_64(k, 11);
    ctx->sched[0x3] = (k);
    ror56_64(k, 11);
    ctx->sched[0x4] = (k);
    ror56_64(k, 11);
    ctx->sched[0x5] = (k);
    ror56_64(k, 11);
    ctx->sched[0x6] = (k);
    ror56_64(k, 11);
    ctx->sched[0x7] = (k);
    ror56_64(k, 11);
    ctx->sched[0x8] = (k);
    ror56_64(k, 11);
    ctx->sched[0x9] = (k);
    ror56_64(k, 11);
    ctx->sched[0xa] = (k);
    ror56_64(k, 11);
    ctx->sched[0xb] = (k);
    ror56_64(k, 11);
    ctx->sched[0xc] = (k);
    ror56_64(k, 11);
    ctx->sched[0xd] = (k);
    ror56_64(k, 11);
    ctx->sched[0xe] = (k);
    ror56_64(k, 11);
    ctx->sched[0xf] = (k);

    return 0;
#else
    uint32_t hi, lo; /* hi is upper 24 bits and lo lower 32, total 56 */

    /* discard the parity bits */
    lo = (*key++) >> 1;
    lo <<= 7;
    lo |= (*key++) >> 1;
    lo <<= 7;
    lo |= (*key++) >> 1;
    lo <<= 7;
    lo |= (*key++) >> 1;
    hi = lo >> 4;
    lo &= 0xf;
    lo <<= 7;
    lo |= (*key++) >> 1;
    lo <<= 7;
    lo |= (*key++) >> 1;
    lo <<= 7;
    lo |= (*key++) >> 1;
    lo <<= 7;
    lo |= (*key) >> 1;

    /* Use lower 32 bits for schedule, rotate by 11 each round (16 times) */
    ctx->sched[0x0] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x1] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x2] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x3] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x4] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x5] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x6] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x7] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x8] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0x9] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xa] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xb] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xc] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xd] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xe] = (lo);
    ror56(hi, lo, 11);
    ctx->sched[0xf] = (lo);
    return 0;
#endif
}
